Horsepower rating

[thager]

I stumbled on CA emissions tests for the 5.7 and 6.0 liter engines and was surprised by the rated horse power with cat emissions equipment. 5.7 was only rated at 270 and the 6.0 at 340. Really? No wonder new boats need the 6.0 liter. Think I would consider putting new manifolds on my 5.7 and reflash my ECM if I had one.

[east tx skier]

I had a friend who was a MC dealer put an 09 or 08 MCX on a dyno. It's rated at 350 hp by indmar. It came back at 310. He speculated by the time you added all the other losses, exhaust tips, etc., you were looking at about 275 hp.

[ForrestGump]

The delta between advertised and what Ca measured doesn't mean much without knowing how Ca ran the tests. On an engine dyno, an engine will show vastly different ratings based on the way it's dressed(ie is it tested with a raw water pump pushing water), the correction factors used, whether you do a sweep test or step test, the rpm they made the pull too, etc. In some emissions tests, they only go to a certain rpm point or speed. I wouldn't read too much into that without knowing that information.

 

 

[Brady]

In Utah, skiing at some of the lakes shows at least a 20 percent in horsepower. This is mainly due to the fact that we are at such a high elevation. I guess my question is this: does it even matter on these boats? With the mid engines, the torque seems to be absolutely sufficient and with a different prop, these boats seem to do just fine--even with the smaller engines. My "other" boat caused me so much pain and suffering to increase the horsepower. I am guessing around 50 bucks per 1 horsepower increase. That gets pricey--and the higher you go, that number gets worse. @SkiJay would know more about all this, since this was his life. As a side, I had a snowmobile once that was running 290 hp on the dyno. It was a hill climber and it scared the beejesus out of you when you opened it up. That only cost me an additional 10k to get that one dialed in.

[east tx skier]

@ShaneH, fair point. I haven't kept in touch with this guy to get that info. He was a MC dealer and avid skier at the time he did this. I guess I assumed it was on some sort of cooling system, i.e., raw water pump.

[thager]

Point is there needs to be some kind of industry standardization. I find it funny that the same exact engine from the same maritime engine producer has a different HP rating in a different boat manufacturers tow boat?

[ForrestGump]

That's a pipe dream. Hell, there's no real industry standard for car engines, either. Other than SAE net standard J1349 and/or J1995. And in fact, that's not accurate because the manufacturers can play games with where in the curve they rate the engine. I've engine dyno'd a LOT of engines over the years and you'd be surprised where they come out.

 

SAE J2373 is a certification that has a few mandates such as a specific test standard such as J1349 or J1995 being performed in an ISO9000/9002 certified lab, and being witnessed by an SAE approved "witness". But conformance to J2373 is completely voluntary.

 

So if the automobile manufacturers can't test to one standard, you expect marine manufacturers to do it?

[thager]

@ShaneH Don't expect it. Just sick of the games. I have a little mechanical background and know most of the the Bull. Most of the boating public doesn't have a clue which is why I like to stir the pot. Get them thinking. You sell boats don't you? Did I mention,"I hate winter!"

[6balls]

Hmm. Not saying I'm actually pushing 310 in my GT40 SN196, but if I am, my bro's '06 MC TT with MCX is certainly pushing 350...maybe more. That same MCX easily out-performs my buddies '02 MC TT which has basically the same hull and the supposed 400 hp caddy in there.

A lot may depend on HP and torque curves. The Caddy does run higher top end if you give it long enough...but mostly is full of sound and fury, signifying nothing if one stuffs the throttle mid range. No comparison on hole shot to 36 mph...goes to the drive by wire MCX by a long shot.

[BraceMaker]

@thager - I'm with you, recall what happened to Briggs - that lawsuit went from HP ratings to CC displacement.

 

Check out any lawn tractor these days, the companies don't even give you an HP figure, which atleast gets rid of the guess work.

 

I think the reality of boat engines would be more of a "performance index" And I think more accurate or rather more important would be avg fuel consumption per hour, 0-36 mph in seconds, or perhaps how many feet to 36 mph?

[ForrestGump]

@6balls Your example could have very little to do with power and a lot to do with trans gearing and prop selection.

[6balls]

@shaneh, in total agreement.

[Razorskier1]

@ShaneH -- true for the boat to boat compare. My boat is a TT so it has the powerslot. It came with a four blade OJ and now is a 3 blade Acme (can't recall pitch, in another thread on here somewhere). Boat pulled hard with both. I like the three blade Acme better as it seems better all around -- more hole shot, more acceleration, and higher top end (4mph). As an aside, it also resolved a "wheel shake" that I had when the boat was wide open with the 4 blade (my mechanic suggested that the Acme would solve that issue and it did).

 

As an aside, I have driven other TTs (all newer) and felt like I had to put the throttle all the way down to get anything out of them (this includes both MCX and the new Ilmoors). Variations seem significant across motors.

[BraceMaker]

Did you keep track of the different TT's in terms of hours on the clock?

 

I've also been curious about the amount of drag that a strut misalignment can create.

 

[Greg Banish]

I have worked directly with one of the ski boat engine manufacturers. They operate in a very different environment than my OEM automotive clients. The ski engine guys make one engine and sell it to several boat companies, who in turn are each free to claim a HP rating that is +/- some percentage from what the engine guy tested it at. Obviously, the boat guys lean toward the top end of what they can claim, with some pushing the envelope more than others even though they are using identical engines. For an automotive OEM SAE J1349 requires +/-2%, no questions as long as you test in the exact conditions specified. Aftermarket dynos don't usually come close to replicating these conditions.

 

All of that said, I still firmly believe there's room for boost 4cyl engines in the tournament boat market. As long as you can generate the necessary prop thrust (combination of torque and speed), the holeshot should be identical to the skier. Making 270hp out of supercharged/turbo 4cyl is child's play today.

[kmenard]

A lot of the car mans are going boost to be able to make power and emissions. Wave runners are doing it too, it would surprise me if boat mans don't follow suit. Btw...when I had my boat in AZ, it was amazing the difference between say Canyon lake and Powell. It was like someone disconnecting spark plugs.